Basic Operators

Whenever you write a program in Python, the language offers you a variety of tools to perform arithmetic, logical, and comparison operations efficiently. These tools are called operators, and they form the backbone of manipulating data in your code.

In this lesson, we will explore the basic operators in Python. By the end, you will understand how to use arithmetic, assignment, comparison, logical, and bitwise operators with confidence, which will empower you to write powerful expressions and make decisions in your programs.

Let's dive right in and explore each category with detailed explanations and examples.

Arithmetic Operators

Arithmetic operators allow you to perform mathematical calculations. These are the most common operators you'll encounter when dealing with numbers.

Notice the subtle differences between / and //. The / operator always returns a floating-point number, even if the division is exact, while // returns the quotient after floor division (i.e., it discards the fractional part).

# Basic arithmetic operations
a = 15
b = 4

print("Addition:", a + b)          # 19
print("Subtraction:", a - b)       # 11
print("Multiplication:", a * b)    # 60
print("Division:", a / b)           # 3.75 (float result)
print("Floor Division:", a // b)   # 3 (integer quotient)
print("Modulus:", a % b)            # 3 (remainder)
print("Exponentiation:", a ** b)   # 50625 (15^4)

Assignment Operators

Assignment operators not only assign values to variables but can also perform operations on the variable and then assign the result back to it. This makes your code concise and readable.

These compound operators help to simplify and shorten your code when you need to update the value of a variable based on its current value.

x = 10
print("Initial value:", x)

x += 5      # x = x + 5
print("After += 5:", x)

x *= 2      # x = x * 2
print("After *= 2:", x)

x %= 6      # x = x % 6
print("After %= 6:", x)

Comparison Operators

Comparison operators are essential for decision-making in your programs. They compare two values and return a bool value — either True or False.

Comparison operators are often used in if statements and loops, controlling the flow of your program based on conditions.

age = 20

if age >= 18:
    print("You are an adult.")
else:
    print("You are a minor.")

print("Is age equal to 20?", age == 20)
print("Is age not equal to 18?", age != 18)

Logical Operators

Logical operators combine multiple boolean expressions and return a boolean value. They are crucial for building complex decision-making conditions.

These operators are often used inside conditional statements to check multiple conditions simultaneously.

username = "admin"
password = "secret"

if username == "admin" and password == "secret":
    print("Access granted.")
else:
    print("Access denied.")

is_logged_in = False
if not is_logged_in:
    print("Please log in first.")

Bitwise Operators

Bitwise operators work on the binary representation of integers. They are more advanced but extremely useful in certain domains like networking, cryptography, and performance optimization.

If you're unfamiliar with binary numbers, don't worry! You can think of bitwise operators as tools that manipulate the "bit patterns" that make up integers behind the scenes.

x = 5   # binary: 0101
y = 3   # binary: 0011

print("x & y:", x & y)    # 1 (0001)
print("x | y:", x | y)    # 7 (0111)
print("x ^ y:", x ^ y)    # 6 (0110)
print("~x:", ~x)          # -6 (two's complement)
print("x << 1:", x << 1)  # 10 (1010)
print("x >> 1:", x >> 1)  # 2  (0010)

Operator Precedence Quick Overview

Here is a simplified list of operator precedence from highest to lowest:

• Parentheses: ( )
• Exponentiation: **
• Unary operators: +x, -x, ~x
• Multiplication, Division, Floor Division, Modulus: *, /, //, %
• Addition and Subtraction: +, -
• Bitwise shifts: <<, >>
• Bitwise AND: &
• Bitwise XOR: ^
• Bitwise OR: │
• Comparison operators: ==, !=, <, >, <=, >=
• Logical NOT: not
• Logical AND: and
• Logical OR: or
• Assignment operators: =, +=, -=, ...

Putting It All Together: A Practical Example

Let's create a simple program that calculates the total price of items in a shopping cart, applies a discount, and determines if the total qualifies for free shipping.

# Prices of items in the cart
item1 = 29.99
item2 = 9.99
item3 = 4.99

# Calculate subtotal
subtotal = item1 + item2 + item3

# Apply a 10% discount
discount = 0.10
total_after_discount = subtotal * (1 - discount)

# Check if qualifies for free shipping (total >= 30)
free_shipping = total_after_discount >= 30

print(f"Subtotal: ${subtotal:.2f}")
print(f"Total after discount: ${total_after_discount:.2f}")
print("Free shipping:", free_shipping)

# If not free shipping, add shipping cost
if not free_shipping:
    shipping_cost = 5.99
    total_after_discount += shipping_cost
    print(f"Shipping cost added: ${shipping_cost:.2f}")
    print(f"Final total: ${total_after_discount:.2f}")
else:
    print(f"Final total: ${total_after_discount:.2f}")

This example used arithmetic operators to calculate totals, comparison operators to check if the total qualifies for free shipping, and logical operators to branch logic accordingly.

Summary

Here’s what you should take away from this lesson:

• Arithmetic operators perform basic math operations.
• Assignment operators assign or update variable values succinctly.
• Comparison operators compare values and return boolean results.
• Logical operators combine boolean expressions to build complex conditions.
• Bitwise operators manipulate integers at the binary level.
• Operator precedence determines how expressions are evaluated; parentheses help control this order.

Mastering these operators is essential for writing effective and efficient Python code. As you continue your coding journey, you’ll use these operators daily to manipulate and compare data, control program flow, and implement logic.